J. Gooth, T. Böhnert, J. Gluschke, B. Hamdou, S. Barth, D. Goerlitz, R. Zierold, K. Nielsch:
"Kinetics of the charge ordering in magnetite below the Verwey temperature";
Journal of Physics: Condensed Matter, 26 (2014), 47; S. 472202 - 472206.

Kurzfassung englisch:
In this work the kinetics of the charge ordering in magnetite (Fe3O4) below the Verwey transition temperature TV is investigated in time and energy domain. After excitation by a one-second voltage pulse to destruct the charge-ordered state below TV, an alternating current (AC) is used to perturb its recovery process. Upon warming up to above a temperature Tr(< TV) the charge order recovers despite the ac perturbation, because the temperature-dependent relaxation time becomes shorter than the polarity change of the ac. From the frequency dependence of Tr(f), an activation energy of ΔE = 126 meV is extracted. Below Tr the real part of the ac conductance Greal follows the relation Greal ∼ fα with α = 0.98 ± 0.18, suggesting that the charge reordering is driven by correlated hopping transport. The relaxation time τ = 1/f (Tr ) of the charge-ordered state is determined for temperatures between 70 and 98K and is extrapolated to τ(TV) = 1.6 ms, continuously slowing down its dynamics as the temperature is decreased.

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